Carburetor



Feb. 29 1944.

| H. SHAFF cmaunmo'iz Filed Jan 12, 19:59

' INVENTOR.

ERNEST H. 3HQFF ayflagfgzz e a TTORNEY.

Patented Feb. 29, 1944 UNITED STATES PATENT or-"rice CARBURETOR Ernest H. Shaft, Bryan, Ohio, assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application January 12, 1939, Serial No. 250,480

Claims. (Cl. 123119) This invention relates to carburetors for internal combustion engines and more particularly to carburetors having heat responsive air and fuel proportioning means.

An object of this invention is to provid a carburetor to enhance the starting performance of internal combustion engines, and also to secure a more economical rate of operation thereof.

Another object of this invention is to provide means operable during the starting cycle of operation of an internal combustion engine to dispense fuel thereto, and after the starting cycle to augment the action of the main fuel source during the subsequent period of eng ne ope at on.

Still another object of this inventionis to provide temperature responsive means to control the fuel and air proportioning of the ma n su -ply of fuel in a carburetor for an internal combustion engine, this control of fuel and air proportion ng having no influence on the fixed proportioning of fuel and air used during normal operation of the engine after the warm-up cycle thereof.

Another object of this invention is to rovi e a carburetor having a main fuel jetwith substantially no air-bleed action at the jet durin a relatively short period during the startin o the engine, followed by a period of engine operation during which relatively hot air is supplied to the air-bleed of the main jet until the carburetor proper is warmed, after which air at the prevailing temperature is supplied to the main jet airbleed. 1

A further object of this invention is to provide temperature responsive means associated with the exhaust manifold of an engine to control the main jet air-bleed port of a carburetor.

A further feature of this invention is to provide a carburetor for an internal combustion engine with a heat responsive valve adjacent the exhaust manifold of said engine controlling the entrance to a passage leading to the main jet air-bleed of the carburetor, and a second heat responsive valve controlled by the temperature of the carburetor body proper controlling a port which connects the air-bleed passage directly with the-atmosphere in close proximity to said main jet.

Another desirable feature of this invention is to provide a thermostatically controlled auxiliary fuel supply to the main supply of a carbure tor of an internal combustion engine, wherein the auxiliary supply may be operative only during the starting and warm-up cycles of operation the engine.

Still another advantageous feature of this invention is to provide a vent to the auxiliary fuel line which operates to vary the main fuel supply of a carburetor of an internal combustion engine,

the Vent operating to prevent the auxiliary tube from becoming liquid sealed.

The above and other objects and features of the invention, including various novel and desirable details of construction, will be apparent from the following description of an illustrative embodiment shown in the accompanying drawing, submitted for purposes of illustration only and not intended to define the scope of the invention, reference being had for that purpose to the subjoined claims.-

In the drawing, wherein similar characters refer to similar parts in both views:

Figure 1 is an elevational view partly in section. showing my novel control of the fuel system of a carburetor as associated with the pertinent parts of an internal combustion engine; and

Figure 2 is a fragmentary view partly in section, disclosing the connection of a carburetor main fuel supply air-bleed with the thermostatically controlled air supply line.

Referring to Figure l, a carburetor I0 is mountedon an intake manifold [2 which may be positioned adjacent an exhaust manifold M. Means such as air conveying ducts l6 and it having their lower ends closed or opened in accordance with variation in temperature by thermostatic flap valves 20 and 22 are provided to supply air to the fuel supply jets of the carburetor. It will be understood that these temperature responsive valves may take any desired form known in the art.

The carburetor I0 is provided with an air inlet 30, controlled'by a choke valve 32, which may be controlled by known manual or automatic means. A secondary venturi 34 is positioned to discharge into a primary venturi. 36 anterior to a throttle valve 38. An idling fuel jet 40 is provided to supply fuel to operate the engine when the throttle valve 38 is in or near its closed position, and is fed with fuel by an idling passage 4| of usual design.

Positioned to discharge into the secondary venturi 34 in the usual manner is a main fuel discharge jet 42 having an air-bleed passage 44 Figure 2) which lead from a duct I8, the open end of which may be controlled by a thermostatically controlled valv 22. The 'upper end of duct I8 is preferably of increased diameter as indicated at 45. This enlarged portion may be provided with an a r inlet port 46 on one side immediately adjacent the carburetor body proper, This inlet port 48 may be controlled by temperature refuel from a fuel reservoir 56. A metering orifice I2 is positioned in the fuel Jet 50. The air sup-- ply for Jet 50 may be transmitted through the duct l8 controlled at its lower end by the thermostatically controlled valve 20. The duct [6 is formed with a hump or raised section 58 having at its uppermost portion a vent 60 of restricted size. 7

A third fuel jet 6| having an outlet into the secondary venturi 34 serves to discharge fuel from the acceleration pump, not shown, into the main carbureting passage of carburetor III.

In the operation of this device when starting with a cold engine, the thermostatic valves 22 and 48 will be closed, thus preventing, air from entering the main jet through the air-bleed passage A rich mixture is therefore supplied by the main jet during the starting period. When the engine has started and the exhaust pipe 14 warms up, the thermostat 22 gradually opens to admit heated air from the surface of pipe H to the air-bleed. This heated air flows through the carburetor to raise the temperature of the carburetor proper, thereby preventing ice from forming on the throttle 38 and associated parts adjacent the idling ports 40 to lock the throttle against movement. It has been found that this condition frequently occurs when the humidity of the atmosphere is high, and the prevailing temperature is between 30 and 38 degrees. A more perfect combustible mixture is also supplied to the engine cylinders.

When the carburetor body is sufficiently heated due to the operation of the engine, to a point where hot air is no longer beneficial at the airbleed, the thermostatic valve 48 opens to admit air at the prevailing temperature directly to the air-bleed.

While the engine is cold, the temperature responsive valve 20 is also closed, and the auxiliary fuel jet 50 further enriches the mixture, as fuel is drawn int0.,.the carbureting chamber by the suction created in the ve'n'turis 34 and 35. This additional quantity of fuel is also mixed with air admitted through the vent 60 in the duct l6,

which serves as an air-bleed mechanism when the valve 20 is closed. The raised portion 58 serves as a dam to prevent liquid fuel escaping backward through the duct l6 proper. The vent 60 admits air to prevent a siphoning action in the duct l6 should liquid fuel under any circumstances be present therein. The air admitted through the vent 60 will readily permit the escape of any liquid fuel or moisture which may accumulate at the opening at the lower end of duct l6 controlled by the thermostatic valve 20 which would in any way restrict the ready entrance of air.

Thus it will be seen that in starting an internal combustion engine fitted with a carburetor embodying my novel fuel system, a rich combustible mixture of air and fuel is initially supplied to the combustion chambers of the engine, both by the main jet 42 and by the auxiliary fuel Jet 50. As the temperature rises, the temperature responsive means functions to provide a mixture of fuel and air proportioned to give best results as the engine progressively warms up, and to provide a mixture which will give desired power and economical performance as the engine becomes hot.

It will be seen that either duct I6 or duct I8,

with its associated parts, may be omitted if de- -sage H in addition to the devices disclosed.

Although this invention has been described in connection with certain specific embodiments,

the principles involved are susceptible of numerous other applications that will readily occur to persons skilled in the art. The invention is, therefore, to be limited only as indicated by the scope of the following claims.

I claim:

1. In combination with an internal combustion engine having intake and exhaust manifolds, a carburetor comprising a main fuel supply jet, means closely associated with the exhaust manifold to variably control air introduced with the fuel at said main jet, secondary heat responsive control means closely associated with the carburetor to render ineffective the action of the first mentioned control means associated with the exhaust manifold.

2. A carburetor having a throttle valve, a choke, valve, a fuel supply outlet for the carburetor comprising a main fuel jet, an air-bleed therefor, a source of heat, said air-bleed connected to the heat source by a duct for transmitting heated air tothe air-bleed, thermostatically actuated means controlling the inlet of the duct at the heat source, means located between the inlet of the duct and the air-bleed to admit cooler air unrestrictedly to the duct when normal operating temperatures are attained, and an auxiliary jet comprising thermostatically controlled means to enrich the fuel-air ratio at low temperatures and lean the fuel-air ratio at hightemp'eratures.

3. In a carburetor for an internal combustion engine, a main fuel nozzle, a source of air at relatively high temperature, a second source of air at relatively low temperature, means connecting said air sources with the,nozzle for bleeding air thereinto, and thermostatic means for varying the relative amounts of air bled into the nozzle from said sources whereby no air is bled into the nozzle during the starting period of a cold engine, heated air is bled into said nozzle while the engirte is operating at subnormal operating temperature, and cold air is bled into the nozzle :vhen the engine is operating at normal temperaure.

4. Ina] carburetor for an internal combustion engine, a fuel nozzle, means for bleeding warmed air to said nozzle, temperature responsive means for cutting off said air when the engine temperature is low, and temperature responsive means for supplying a relatively large volume of cooler air to the first mentioned means when the engine attains normal operating temperature, said last mentioned temperature responsive means being adapted to cut off the supply of cooler air when the enginetemperature is low.

5. In a carburetor for an internal combustion engine having an exhaust manifold, a body portion, a fuel nozzle, means for bleeding air to the fuel nozzle, said means having a plurality of air inlets, means responsive to the temperature of said exhaust manifold for controlling one of said air inlets, and means responsive to the tempera- ERNEST H. SHAFF. 

